Citizen Scientists to Reboot NASA Space Probe Launched in 1978

The ISEE 3 reboot project has pushed back the date for breaking the spacecraft out of solar orbit. This is now planned for between June 30th and July
2nd. This delay became practical when it was realized that the ISEE 3 was on a more favorable trajectory than expected. Much less fuel would be
required to move it into the new desired orbit, even on a later date.
They will use the Arecibo dish in conjunction with some in the NASA Deep Space Network to get more accurate positional fixes on the spacecraft. This
will occur on June 18th through 22nd, and on July 3rd, 4th, and 6th. This will give positions for the ISEE 3 both before and after the planned
maneuver.
The project will use the 34 meter dishes of the Deep Space Network, near Goldstone, California; Madrid, Spain; and Canberra, Australia.

The story of the ISEE 3 reboot mission made the front page of the Sunday New York Times, see link, below.
A simple thrust maneuver is tentatively planned for June 21st. This will increase the spin rate of the spacecraft slightly, in order to improve its
stability. This is necessary before the orbit-changing maneuver can be done. Its spin has run down a bit from the time of its launch, 36 years ago.
This maneuver will also be the first test of the thrusters, and thruster control by radio, since the ISEE 3 reboot project took control of the
spacecraft. www.nytimes.com...

A bit of a setback for the ISEE 3 reboot project. The thruster action to improve the spin stabilization of the ISEE 3, set for today, had to be
postponed. The reboot team could not confirm that test commands had been properly and consistently received. They are currently investigating this
problem.
Things had been going so remarkably well for the project, it seems inevitable that a problem would eventually crop up.

The ISEE 3 reboot team used the NASA Deep Space Network today, to determine the distance of the spacecraft. It is necessary to know its position to a
high accuracy, in order to plan the maneuver that will change the orbit. This is the first time since 1999 that the Deep Space Network has
communicated with the spacecraft.
The ISEE 3 has successfully carried out some commands sent to it, but there still appears to be a problem with it doing so consistently. Another,
longer session using the DSN is planned for tomorrow.

The ISEE-3 reboot team reports that the spacecraft fired its thrusters in response to their commands, successfully carrying out the spin stabilization
maneuver today. Next comes the maneuver to change the ISEE-3's solar orbit into a halo orbit near Earth, and the perilous pass very near the Moon,
around and behind it. The team adds that data was received from the magnetometer aboard the spacecraft yesterday, revealing signs of a recent solar
event.

The ISEE-3 reboot team reports that they will attempt the all-important maneuver to break out of Solar orbit tomorrow, at 16:42 to 19:29 GMT (12:42 to
3:29 p.m. Eastern Daylight Time; 9:42 a.m. to 12:29 p.m. Pacific Daylight Time.) The commands will be sent from the 300 meter (1000 foot) Arecibo
radio telescope. If the thrusters succeed in fining, they will arrange another ranging session to confirm that the spacecraft is now in a suitable
orbit.

The plan for Tuesday was to attempt 435 thruster pulses, divided into seven segments. The first segment, of 63 pulses, went well. Problems were
encountered during the second. The remainder of the thrust segments were canceled for the day.
The team will be looking at the data, and working out what needs to be done. They have another session at Arecibo booked for Wednesday, at the same
time as the one on Tuesday. In addition to resolving the persisting problem of intermittent response to commands, they will presumably have to
recalculate the thrust, given the distance the spacecraft will travel in 24 hours.

Yes, they want to put the spacecraft in a halo orbit near the L1 point, a million and a half kilometers Sunward from Earth. They plan to deliver about
7 meters per second of thrust, very soon. This will send the ISEE-3 very near the Moon on August 10th.
The Moon's gravity will bend the trajectory, and eventually have it looping back around again past Earth. Earth's gravity will then bend the
trajectory again sending it on to the halo orbit. See link below, for a diagram of the proposed route of the spacecraft: images.spaceref.com...

“There was no burn and we detected no acceleration and nothing was coming out of the engines,” NASAWatch.com Editor Keith Cowing, who
spearheaded the ISEE-3 Reboot Project along with entrepreneur Dennis Wingo, said in a July 9 phone interview.

Yes, Keith Cowing strikes a pessimistic tone in that Wednesday phone interview. His Wednesday evening blog on Facebook, though, seems to hold open
the hope that further troubleshooting might resolve the problem.
He does allude to a 'plan B' of receiving science data from the spacecraft for a few months, even if it remains in solar orbit, should it
prove impossible to put the ISEE-3 into a halo orbit near Earth.
If yesterday's Facebook blog is contradicted by a later statement more in line with the tone of the interview, then I will conclude that the
reboot mission has essentially failed.

A number of news media have been saying that the ISEE-3 reboot team have given up on redirecting the spacecraft into an orbit near Earth. A Friday
morning blog on Facebook, written by Keith Cowing, spokesman for the project, tells a very different story.
He reports that the team spent all of Thursday with propulsion experts, and that a number of troubleshooting measures were developed. Among these:
applying heat to the hydrazine fuel tank, and clearing the (possibly) blocked fuel lines by commanding the ISEE-3 to execute a multitude of thrust
pulses. Cowing reaffirms that they have "most certainly not given up".
Another communication session with the spacecraft is planned for today, again through the Arecibo radio telescope.

The ISEE-3 reboot team has released a long, complex, and highly technical statement. The gist of it is as follows:
There probably is pressurizing gas and fuel still available to guide the spacecraft. It was previously thought that the pressuring gas, which drives
the fuel into the thrusters had somehow leaked away over the years.
It appears that the thrusters may have failed to work properly, when last tried on July 8th and 9th, for one or both of the following reasons:
An excess of the pressuring gas, or gases from the decomposition of the fuel, or both may have accumulated in the fuel lines, preventing the thrusters
from firing.
During the attempts to apply thrust to the spacecraft, electrical power to the fuel line valves was not turned on for much of the time. These valves
permit fuel to flow to the thrusters. Without power the valves would remain closed.

Tomorrow, they will open the valves, and try to clear the fuel lines of any gasses that may be blocking them, hoping the the thrusters will begin to
work again. The communication session runs from 16:19 to 19:05 GMT (12:19 to 3:03 p.m. Eastern Daylight Time, and 9:19 a.m. to 12:03 p.m. Pacific
Daylight time.).

Wednesday's attempt to return the ISEE-3 thrusters to action produced a small amount of thrust, enough to change the spacecraft's course slightly.
Another attempt will be made today (Friday) starting at 16:13 GMT, (12:13 p.m. EDT, 9:13 a.m. PDT) and running for about three hours, thereafter. At
least part of this session should be narrated live, on Twitter.

After trying a number of things to make the thrusters work again, over the last several days, the ISEE 3 reboot team has had to concede that they will
not be able to bring the spacecraft back into an orbit near Earth. They still hope to do some science with it, as some of the instruments are
apparently still working.

There is some uncertainty about how long they will be able to communicate with the spacecraft, as it moves away from Earth again, in its independent
solar orbit. Much apparently depends on their ability to access the Arecibo antenna or NASA's Deep Space Network.

Although the propulsion system isn't working anymore, after more then 30 years the scientific instruments of the spacecraft are still functional and
ready to take some last screens of the moon, before it passes away.

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